Abstract: Addressing the problem of out-of-tolerance of the steel plate blunt edge height during the milling process of the edge milling machine of the UOE welding pipe production line, considering the combined effects by the displacement of the blunt edge milling unit in the direction of the width of the steel plate, and the displacement and deflection movements of the steel plate respectively, the regularity of change of blunt edge height is analyzed systematically, and accordingly the function relationship between the blunt edge height and the offset of the steel plate is established, while height variation curves of the steel plate blunt edge as under the two combined effects are plotted.As a result, the relationship between the change trend of the blunt edge height and the movements of the blunt edge-milling unit and the steel plate is identified, which provides a theoretic basis for quickly finding out the causes for blunt edge height out-of-tolerance, and determining relevant actions for solution of the problem, being of certain reference value for modification of the equipment.